This invention relates to medical devices for removing stones from the kidneys, ureter or biliary duct.
While stones can be removed by direct surgery, it is much preferred that the stone be located by use of an endoscope and removed by endoscopic guidance of a device inserted through a working channel of the endoscope. Examples of instruments used in the past for removal of stones include forceps with axially-directed grasping arms, and basket devices such as shown in Councill U.S. Pat. No. 1,677,671, and baskets with helically arranged wires as shown in Dormia U.S. Pat. No. 2,943,626 and U.S. Pat. No. 4,347,846, e.g. similar to those sold by C. R. Bard, Inc. of Murray Hill, New Jersey.
It is an object of this invention to provide a device that can dislodge and remove stones more effectively than prior devices.